The present invention relates generally to electrical connectors and more particularly, to a connector assembly comprising a receptacle and a header, having a high signal density and enhanced signal carrying capability.
As electronic circuits and components become increasingly miniaturized, the demand for electrical connectors to electrically and mechanically interconnect a first PCB, such as a back panel or mother board, to a second PCB, such as a daughter board has also increased. As existing and additional components are enhanced or added to circuit boards, the electrical connectors that interconnect the circuit boards must accommodate the resulting additional connections. Further, as clock speeds increase other demands are being placed on the electrical connectors that interconnect circuit boards.
Typically, high density connectors have a signal density of 50-65 signals per inch of connector. Conventional techniques to increase signal density have been directed to minimizing the amount of space occupied by each receptacle or contact of the connector assembly. However, closely spaced electrical signals can interfere with one another. The interference phenomenon is referred to as xe2x80x9ccross talk.xe2x80x9d Density and pin count are often viewed interchangeably, but there are important differences. Density refers to the number of contacts provided per unit length. In contrast, the number of contact elements that can reasonably withstand the mating and unmating forces is referred to as the pin count.
As more functions become integrated on semiconductor chips or on flexible circuit substrates and more chips are provided on printed circuit boards (PCBs), each PCB or flexible circuit must provide more inputs and outputs (I/Os). The demand for more I/Os directly translates to a demand for greater density. In addition, many system components are capable of operation at faster speeds than previously. Faster speed can result in the generation of potentially interfering signals, i.e., crosstalk and noise. The connectors used in such high-speed board-to-board, board-to-cable and cable-to-cable communications may be treated for design purposes like transmission lines in which crosstalk and noise become significant concerns. Indeed, the electrical performance of high-speed board-to-board, board-to-cable and cable-to-cable communications is dependent upon the amount of crosstalk and noise introduced at the connector interface.
One method of controlling cross talk is to connect certain terminals of the high density connector to grounded conductive areas of a printed circuit board. This solution is provided externally to the connector and provides for flexibility of design. In particular, a designer may configure the number of grounds and/or signals passed by the connector based on the particulars of the connections to the printed circuit board.
For example, U.S. Pat. No. 4,900,258, to Hnatuck et al., entitled xe2x80x9cMulti-port Coaxial Printed Circuit Board Connectorxe2x80x9d, discloses a connector having plural coaxial subassemblies. Each coaxial subassembly is provided with a center contact for passing a signal and an outer contact which is connected to ground. The individual coaxial subassemblies are arranged in rows and columns within the connector assembly which is then mounted at a right angle to a motherboard.
U.S. Pat. No. 5,547,385, to Spangler, entitled xe2x80x9cBlind Mating Guides on Backwards Compatible Connectorxe2x80x9d, discloses an electrical connector assembly comprising a first electrical connector having alignment posts which mate with receiving cavities provided in a second mating electrical connector. The ground contacts which extend from the first connector are longer than the signal contacts so the ground contacts engage respective conductors in the mating electrical connector prior to the signal contacts engaging their respective conductors in order to discharge electrostatic charge to a chassis ground.
According to another method of controlling cross talk, conductive material is disposed between rows and/or columns of signal carrying terminals in the high density connector. The conductive material is generally separated from the signal leads by a dielectric material such as plastic. According to this method, the conductive material is connected to a corresponding grounded conductive area of the printed circuit board. Such connectors have been termed in the art as strip-line or micro-strip connectors. Unlike the first method above, this solution is provided within the connector itself.
For example, U.S. Pat. No. 4,705,332, to Sadigh-Behzadi, entitled xe2x80x9cHigh Density, Controlled Impedance Connectorsxe2x80x9d, discloses a modular connector where discrete wafers having signal carrying conductors are stacked together. The discrete wafers are formed having multiple signal carrying contact elements which may be mounted at a right angle to a mother board or daughter board. Locating pins are provided, which are received by apertures in the mother board. Between each wafer is a planar ground element such that a strip line configuration is created.
U.S. Pat. No. 4,806,107, to Arnold et al., entitled xe2x80x9cHigh Frequency Connectorxe2x80x9d discloses a strip line type connector having ground plates that extend from the connector. The ground plates are inserted into a complementary connector and are formed by bending single metal sheets into a U-shape. The extending portion of the U-shaped metal sheet form pairs of ground plates. A flexible connector attached near the base of the xe2x80x9cUxe2x80x9d is connected to a ground contact on a mother board.
U.S. Pat. No. 5,632,635, to VanBesien et al., entitled xe2x80x9cElectrical Connector Arrayxe2x80x9d, discloses an electrical connector array having a plurality of signal contacts separated by a ground strip. The ground strip is provided with connection points which are spaced in an manner to minimally affect the particular routing of the connector.
In addition to the above-mentioned methods of controlling cross talk, the dielectric material used to separate conductive leads may affect cross talk by altering the characteristic impedance of the connector. Conventionally, non-conductive materials such as plastic are used as a dielectric to insulate regions between conductors within a connector.
For example, U.S. Pat. No. 4,070,048, to Hutchinson, entitled xe2x80x9cControlled Impedance Connectorxe2x80x9d, discloses a connector for a computer backplane or printed circuit board where the signal carrying conductors are embedded in a dielectric block. A metallic foil is provided as a ground plane between rows of right angle pins. The metallic foil is connected with ground pins which are spaced apart in the connector assembly and are used as a reference to all signal carrying conductors and to obtain a desired impedance. Hutchinson also discloses embedding a flexible micro strip having signal carrying conductors and a ground plane within the dielectric block. Ground reference sockets, provided at each corner, are connected to the round plane on the micro strip.
While the prior art teaches connectors having a high pin count, the prior art connectors fails to teach a connector having a signal density which meets the demands of ever-increasing miniaturization of printed circuit boards. The prior art also fails to address increasing signal density by eliminating space consuming dielectric and insulative elements from the header array, such as plastic slots into which circuit cards are inserted. Moreover, the prior art fails to adequately address the problem of increased insertion forces that are generated and sequential mating concerns when a large number of header contacts are inserted into a receptacle. Still further, the prior art fails to teach a connector that uses air as a dielectric material to insulate signal leads while adequately reducing cross talk and maintaining a proper characteristic impedance.
In view of the above, the present invention, through one or more of its various aspects and/or embodiments is thus presented to accomplish one or more objects and advantages, such as those noted below.
A primary object of the present invention is to provide connector assemblies having a configuration characterized by enhanced signal carrying capacity, a low signal to ground ratio and preferably minimal cross talk, as required by the particular application for which the connector is intended.
The present invention provides a header, a receptacle, and a high density connector assembly comprising a combination of the receptacle and the header adapted to mate with each other. In accordance with an aspect of the present invention, a header for mating with a receptacle is provided which includes an insulative body comprising an outer surface and defining at least one notch, a plurality of tails extending through the insulative body, a guide pin integrally formed within the insulative body, and a plurality of conductive blades disposed on the outer surface of the insulative body, where each of the conductive pins being in electrical communication with one of the plurality of tails.
According to a feature of the present invention, the plurality of conductive blades are disposed in columns and at least three of the conductive blades are of unequal lengths. According to another feature, the at least three conductive blades are disposed in the columns such that adjacent conductive blades in each of the columns have different lengths.
According to yet another feature, each of the plurality of tails in a first column is aligned with a first edge of a corresponding conductive strip, and each of the plurality of tails in an adjacent column to the first column is aligned with a second edge of each of the conductive blades, the second edge being an opposite edge of the conductive strip with respect to the first edge.
According to a further feature, the at least one notch is provided at a corner of the insulative body.
According to a feature, the header further comprises a plurality of notches and a plurality of guide pins integrally formed within the insulative body.
According to another feature, the header is adapted to be joined on a printed circuit board to at least one other header. According to yet another feature, the joined headers may be mounted to opposing faces of a printed circuit board.
According to another aspect, a receptacle for mating with a header is provided which includes an insulative assembly frame, a plurality of pins extending through a first member of the insulative assembly frame, a plurality of tails extending through a second member of the insulative body, a plurality of leads connecting the plurality of pins to the plurality of tails, and a non-conductive protrusion extending from the second member of the insulative body.
According to a feature of the present invention, the first member and the second member are formed at a right angle.
According to another feature, the insulative member further comprises a base portion, a dimension of the base portion being defined by a distance the second member is offset from an edge of the first member.
According to yet another feature, a surface of the first member, through which the leads extend, is formed at a predetermined angle other than a right angle with respect to the second member. According to a feature, a surface of the first member, through which the leads extend, is formed at a right angle with respect to the second member.
According to another feature, the receptacle further comprises a diagonal member, the diagonal member extending from an end of the first member opposite the second member to an end of the second member opposite the first member.
According to yet another feature, the receptacle further comprises a third member, the third member disposed substantially parallel to the first member; and a fourth member, the fourth member disposed substantially parallel to the second member.
According to a further feature, a region of intersection of the first member and the second member has a cross section defining a triangular. According to yet another feature, a region of intersection of the first member and the second member has a cross section defining a semi-circular arc.
According to a further feature, the receptacle is adapted to be stacked with at least one other receptacle and the stacked receptacles may be mounted within a receptacle housing.
According to yet another aspect, a connector assembly is provided which includes the header and a receptacle housing containing at least one of the receptacles of the present invention. The receptacle housing and the header are adapted to be mated to each other, and each of the receptacle pins is adapted to mate with a corresponding one of the conductive blades when the receptacle housing and the header are mated.
According to a feature of the present invention, the conductive pins are disposed in columns on the outer member of the insulative body and at least two of the conductive pins in each of the columns having unequal lengths. The at least two conductive pins are disposed in the columns such that adjacent conductive pins in each column have different lengths.
According to another feature, the receptacle housing is adapted to mate with the header in accordance with a location of the guide pin.
According to yet another feature, the header is arranged as an array of plural headers having plural guide pins which provide for at least two points of guidance of the receptacle upon mating with the header.
According to still another feature, a plurality of notches and a plurality of guide pins are provided where the plurality of guide pins are aligned in a row.
According to a further feature, the receptacle housing is adapted to mate in an orientation parallel to the row of guide pins.
According to another feature, the header is arranged as an array of plural headers having plural guide pins which provide for at least two diagonally opposed points of guidance of the receptacle upon mating with the header.
According to yet another feature, the plurality of conductive pins and the plurality of terminals are arranged to have an interstitial ground pattern.
According to still another feature, a leading portion of each of the plurality of terminals is disposed within the receptacle housing, and a remaining portion of each of the plurality of terminals is external to the receptacle housing.
According to yet another feature, the header comprises a plurality of conductive pins arranged in parallel and the receptacle housing comprises a plurality of leads arranged in parallel, such that signal lead and ground lead connections between first and second printed circuit boards or back planes follow substantially parallel paths.
According to a further feature, an edge of one of the leads is arranged to be proximate to an edge of an adjacent lead, and a distance separating edges of the leads in the connector assembly is less than a thickness of the leads.
According to another aspect of the present invention, a header adapted to be mounted on opposing sides of a printed circuit board is provided which comprises an insulative body comprising an outer surface, a plurality of tails extending through the insulative body, and a plurality of conductive pins disposed on the outer surface of the insulative body where each of the conductive pins being in electrical communication with one of the plurality of tails. A plurality of tails of a first header, mounted to a first side of the printed circuit board, are fixed within corresponding holes in the printed circuit board, and a plurality of tails of a second header, mounted to second side of the printed circuit board, are fixed within the corresponding holes in the printed circuit board.
Other features of the invention are described below.